This invention relates to an air chuck for a compressed air hose used to inflate automobile tires or the like, and more particularly to such air chuck molded of synthetic resin material.
Conventional air chucks are made of metal, usually a brass alloy, and are typically machined on automatic screw machines. Generally, these prior art air chucks have a body with a bore therethrough adapted for connection to an air hose. A check valve is provided in the body which is normally held closed by air pressure and which is moved to an open position when the air chuck is applied to a valve stem on a tire to be inflated. The air chuck has a cap which has an opening therethrough for reception of the valve stem. The cap is threaded into a bore in the air chuck body to hold the check valve in assembled position. This bore in the air chuck body has internal threads engageable with external threads on the cap, these internal threads extending into the chuck body from the outer end of the bore. With the cap screwed into the bore, the cap extends out beyond the body.
In use, air chucks are often subject to severe abuse as they may be run over by automobiles or trucks, they may be thrown with whiplike action on the end of an air hose against the concrete floor, and they are subject to abraision as they are dragged along a driveway or floor. Due to the increasing cost of material and labor, conventional brass air chucks are expensive to manufacture.
In developing air chucks molded of synthetic resin material, it was found necessary to keep the size of the air chuck as small as possible (e.g., approximately the size of conventional brass air chucks) so as to permit the new air chuck to be applied to tire valve stems or other air fittings in cramped quarters (e.g., certain automobile hub cap designs limit access to the valve stem). Even the strongest available synthetic resin material does not have the modulus of elasticity or compressive strength of brass. This presents severe problems in designing an air chuck of synthetic resin material of relatively small size having the same strength and resistance to severe abuse as a conventional brass air chuck.